A brief anatomy lesson might help you understand what an odontoid fracture is and where it’s located. First of all, the area affected is the second cervical (neck) vertebra. At the very top of the cervical spine is the atlas bone labeled C1. Directly underneath the atlas (C1) is the axis bone, also known as C2. C2 or the second vertebral bone is our destination.
The axis (C2) has a knob of bone that is attached to the main body of the vertebra. It sticks straight up and is called the dens or odontoid process. The dens pokes up through the opening of the atlas (C1) above the axis (C2). A series of complex ligaments holds the skull on top of the atlas. You can nod, shake, tilt, and turn your head — all done as the skull moves around the pivot point of the upper cervical spine.
A fracture of the odontoid process (dens) can create instability of the head on the spine. A type II odontoid fracture extends through the base of the dens. It is the most common type of fracture in this area. Without treatment, difficulty breathing, paralysis, and even death can occur.
This type of fracture occurs most often associated with a car accident or a traumatic fall from a height (e.g., off a ladder, from the roof top). In older adults, a simple fall at ground level can be enough to cause this type of fracture. It’s a serious break because of the close proximity of the spinal cord right there inside the axis and the atlas. If the broken bone gets displaced, the jagged edge can cut right through the spinal cord.
Even when the broken bone remains in place, bleeding into the area from the injury and swelling from the inflammatory and healing process can put pressure on the spinal cord. If unattended, the resulting neurologic damage can be permanent. Surgery is often done to stabilize the area until bone union and healing are complete.